Proving that some economic policy arguments never die, the old fight over a minimum wage has shrugged off the Great Recession and is gaining strength.

Labor unions are planning pickets Thursday at fast-food restaurants in 100 cities, including San Diego, to demand a $15-an-hour wage for workers.

A similar protest this summer at a San Diego Wendy's drew more media and union officials than workers. But regardless of turnout, organized labor’s point is being made.

In September, Gov. Jerry Brown signed legislation raising California’s minimum wage from $8 to $10 an hour by 2016. President Barack Obama backs a bid by congressional Democrats to increase the national minimum from $7.25 to $10.10 and peg future boosts to inflation.

Such efforts trace to 1938, when President Franklin Roosevelt enacted a wage floor of 25 cents per hour. The arguments for and against remain familiar.

It’s hard to raise a family on a minimum-wage job.

In San Diego, just covering the bills with a 40-hour workweek requires $11.38 an hour for a single adult, and $22.83 for one adult and child, according to a calculator constructed by Amy Glasmeier, a professor of urban planning at Massachusetts Institute of Technology. Her figures don’t include savings, vacations or other basics.

Basic compassion requires leaders to weigh options whenever able-bodied people are working full time and still hover at the edge of poverty.

On the other hand, minimum-wage laws destroy jobs. Raising the minimum by 10 percent generally reduces employment among teens, who typically hold low-wage jobs, by a range of 1 percent to 3 percent.

At least that was the consensus finding of a congressional study in 1981. Economists found that such wage mandates force business owners to either make do with fewer workers or automate.

A refresher course on retail automation is available at any automated teller machine or self-service gas station.

As for flipping burgers, a San Francisco startup says it’s built a machine that produces 380 burgers an hour, with custom grinds of meat and fresh-cut tomatoes on every patty.

Politicians lose more elections over high unemployment than low wages, so Congress allowed the federal minimum to drift lower over the years compared to inflation.

But some states continued to raise minimums, allowing economists starting in the 1990s to conduct “natural experiments” on job losses. One frequently cited study by David Card and Alan Kreuger (who both later advised Obama) found no job losses among fast-food workers in neighboring states with different wage floors.

“That doesn’t mean we shouldn’t do it; it means we should think about the trade-offs,” said David Neumark, a UC Irvine economist who co-authored a comprehensive review of such research in 2007.

Even if society decided that a “living wage” was worth tossing thousands of low-wage earners out of work, that doesn’t necessarily equate to greater social justice.

About one third of minimum-wage workers live in households that earn $50,000 a year or more, Neumark says.

This means that, like most government interventions in the economy, much of the benefit will flow to the middle class.

The best evidence suggests that lawmakers would help more truly needy people if they stuck to direct assistance, such as the Earned Income Tax Credit, and stopped tinkering with the labor market.

But even an enlightened government would still leave us with the problem of “bad jobs,” to use the words of MIT management professor Zeynep Ton, who’s spent the last 10 years studying retail operations.

Ton finds that the best-performing retailers, such as Costco and Trader Joe’s, pay substantially more than competitors because they’ve figured out how to boost productivity.

For example, Costco generally uses more workers per shift and pays an average $20 an hour compared to $13 by Sam’s Club, the warehouse club owned by Walmart. Yet Costco is more profitable, scores better on customer service, and sells more per employee.

Efficient retailers invest heavily in training. They over-staff compared to competitors, using predictable work schedules instead of last-minute changes.

It’s possible that high wages are attracting the best workers to places like Costco and Trader Joe’s, raising the question of whether such productivity gains are scalable across the entire retail industry, let alone fast food.

However, Ton’s work threatens the old saw that competition automatically drives down wages. Great management may be the only cure for lousy wages.